/**
 * \* Created with IntelliJ IDEA.
 * \* User: 冯若航
 * \* Date: 2021/5/18
 * \* Time: 17:07
 * \* To change this template use File | Settings | File Templates.
 * \* Description:
 * \
 */
public class ListNode {
      int val;
      ListNode next;
      ListNode() {}
      ListNode(int val) { this.val = val; }
      ListNode(int val, ListNode next) { this.val = val; this.next = next; }
}